Sketch of The Doodler, who killed gay men in San Francisco in the 1970s.

SAN FRANCISCO - San Francisco Police's cold case unit is taking a closer look at an unsolved serial killer case from the 1970s, after questions from 2 Investigates reinvigorated interest in the string of murders.

The killer, known as "The Doodler," stalked victims in San Francisco's Castro District for nearly two years in the mid-70s.

The Doodler was described as an artist who would sketch strangers he met in local bars and use the drawings to strike up conversations with the men. He’d leave with his sketch subject from the bar, have sex with them, and later stab the man to death.

The Doodler was active in San Francisco between January 1974 and September 1975. At the time, police believe they had identified and detained a suspect who they could link to at least 14 murders and three knife attacks. But no charges were ever brought.

2 Investigates has been looking into "The Doodler" case for months, and has found at least five murders between 1974-75 that may be linked to the serial killer. One victim was found in Golden Gate Park and four others were found in various locations along the shoreline including Ocean Beach.

KTVU brought our own investigation and questions to the current cold case investigator at SFPD, Inspector Daniel Cunningham, who agreed to take a look at the old case file. In subsequent conversations with 2 Investigates, Cunningham agreed that the five murders appear related and were likely committed by the same person but could not confirm. Back in 1975, police released a sketch of the suspected killer based on the description provided by at least one surviving victim.

Earlier this year, Cunningham told KTVU that he would contact several men who had survived attacks by "The Doodler" and have since moved out of state, in hopes of garnering more information and producing an updated suspect sketch. That new sketch is yet to be released.

On Wednesday, CNN erroneously reported that police had identified a suspect more than 40 years after the murders. But SFPD Sgt. Michael Andraychak says CNN's story is not correct. "Contrary to rumors this morning, there are NO new developments and there is NO press conference scheduled," Andraychak wrote in a public statement.

The police department also released a press release Thursday clarifying the status of the case:

While no connections have been made between the “Doodler” attacks and the five homicides, investigators in the SFPD Homicide / Cold Case Unit are working to determine if the same suspect is responsible for both sets of crimes.

A new forensic sketch that shows an “age progression” of the suspect has been created, however, SFPD Investigators have additional follow up steps to take before they can release that sketch publicly.

The Doodler's last victim died in the summer of 1975.

2 Investigates spent months combing through microfilm of newspaper articles from the mid-70s, KTVU's own historic film archive, and other decades-old sources to piece together the timeline of the investigation and the roadblocks that hampered detectives at the time.

According to an article in the San Francisco Sentinel, a paper serving the LGBT community since 1974, some of the survivors -- including a "well known" entertainer and a diplomat -- refused to testify in fear of outing themselves as gay.

The paper interviewed Harvey Milk, who said "I can understand their position. I respect the pressure society has put on them."

The paper also wrote that "police believe the man committed the murders after feeling shame over his homosexual experiences.

2 Investigates has spent months attempting to track down survivors of the notorious killer, and detectives who worked on the case in the 1970s. But due to the long period of time that has passed since the first murders, many of the key players in the case have since died. "The Doodler's" last victim was killed in 1975.

It's possible "The Doodler" is also dead, but police estimate if he's alive today the killer would likely be in his 60s.

KTVU also asked SFPD whether the investigators would be reexamining any old DNA evidence, in light of the Golden State Killer case arrest in which detectives compared the killer's DNA with a public online profile. So far, the inspector in "The Doodler" case does not have an answer about whether any viable DNA is even available.

The SFPD Homicide unit says it is still actively working the case and asks anyone with information to contact them at their 24 hour tip line (415) 575-4444 or by testing text a tip to "TIP411" and to begin the message with "SFPD." You may remain anonymous.